Ua ntej, lithium ion roj teeb electrolyte
Electrolyte yog ib qho ntawm plaub yam khoom tseem ceeb rau cov roj ntsha lithium-ion. Cov roj lithium-ion roj yog qhov guarantee rau lub siab-voltage thiab siab zog ntawm lithium-ion roj teeb. Cov kua roj electrolyte yog tsim los ntawm cov tshuaj ua kom muaj zog, cov kua roj electrolyte lithium ntsev, thiab cov khoom siv los ntawm cov khoom tsim nyog, thiab npaj raws li ib qho piv txwv hauv qee yam.
1.1 organic solvent
Cov organic hnyav feem ntau tov nrog lub siab dielectric qhov hnyav nyob hauv ib qho hnyav viscosity hnyav. Feem ntau siv cov tshuaj electrolyte lithium ntsev yog potassium perchlorate, potassium hexafluorophosphate, potassium tetrafluoroborate, thiab lwm yam., Saib ntawm cov nqi, kev nyab xeeb thiab cov zoo li, potassium hexafluorophosphate Nws yog lub ntsiab ntawm cov roj ntsha uas siv hauv cov roj ntsha lithium-ion.
Feem ntau siv cov tshuaj solvents hauv cov roj ntsha electrolytes (ethylene carbonate) (EC) diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), acrylic acid B. Ester (EA), methyl acrylate (MA), thiab cov zoo li no. Cov tshuaj hnyav yuav tsum ua kom nruj nruj ua ntej siv. Lub purity ntawm qhov hnyav yog zoo rau qhov ruaj khov voltage. Dej noo ntawm cov organic solvent plays lub luag hauj lwm tseem ceeb nyob rau hauv kev tsim cov khoom tsim nyog electrolyte. Txo cov dej kom tsawg dua 10-6 yuav txo tau qhov lwj tshuaj ntawm lithium hexafluorophosphate, qeeb ntawm cov decomposition ntawm SEI zaj duab xis, thiab tiv thaiv kom txhob muaj roj nce siab. Cov txheej txheem noo noo tuaj yeem ua tiav los ntawm molecular sieve adsorption, atmospheric lossis nqus distillation, thiab kev taw qhia txog kev siv roj. Txhawm rau kom muaj kev daws teeb meem nrog high xionic conductivity thiaj li hais tias lithium ions tsiv mus nyob hauv qhov ntawd, qhov hnyav yog feem ntau yog sib xyaw khoom xws li ethylene carbonate (EC) + dimethyl carbonate (DMC), ethylene carbonate (EC) + diethyl carbonate. Ester (DEC).
1.2 roj ntsha kua roj (electrolyte lithium salt)
Qhov lithium ntsev electrolyte ntsev yog tus nqi ntau tshaj plaws ntawm cov roj ntsha roj ntsha, suav txog 40 feem pua ntawm cov khoom siv electrolyte. LiPF6 yog siv cov roj ntsha lithium feem ntau siv, uas ruaj khov rau qhov tsis zoo electrode, muaj hluav taws xob ua kom muaj hluav taws xob, ua paug loj, ua haujlwm sab hauv, thiab ceev ceev thiab tshem tawm. Txawm li cas los xij, nws yog ib qho tsis haum rau cov dej noo thiab HF, thiab nws cov tshuaj tiv thaiv yuav tsum tau nqa tawm hauv qhov chaw qhuav (xws li lub hnab looj tes). Nws tsis tuaj yeem tiv thaiv kev kub ntxhov siab, thiab kev sib cais ntawm qhov teeb meem tshwm sim ntawm 80 ° C mus rau 100 ° C los ua phosphorus pentafluoride thiab lithium fluoride. . Xav txog tus nqi, kev nyab xeeb thiab lwm yam, lithium hexafluorophosphate muaj qhov zoo ntawm cov neeg ua haujlwm zoo heev, muaj siab oxidation stability thiab tsis muaj pa phem. Nws yog tam sim no tus nyiam lithium ion roj teeb electrolyte thiab tseem siv rau cov roj teeb lithium ion. Lub ntsiab ntawm cov roj ntsha electrolyte. Tsis tas li ntawd, LiBF4, LiPF6, LiBOB, LiFSI, LiPF2, LiTDI thiab lwm yam khoom ntawm lithium ntsev electrolyte systems muaj kev nyab xeeb thiab kev ua haujlwm zoo rau kev ua haujlwm zoo.
1.2.1 Lithium hexafluorophosphate
Tam sim no, txoj kev tshawb fawb txog kev npaj rau ntawm LiPF6 tau raug muab faib ua ob pawg: HF hnyav txoj kev thiab kev sib raug zoo ntawm kev sib raug zoo. Lub HF? Txoj kev siv tshuaj yog qhov tseem ceeb tshaj plaws rau kev npaj rau LiPF6 los ntawm dissolving LiF nyob rau hauv ib qho hnyav HF thiab mam li ncaj qha plaug ib yam khoom uas muaj phosphorus los yog fluorine, thiab evaporating los yog txias lub siv lead ua tom qab cov tshuaj tiv thaiv kom tau ib qhov khoom tiav. Txoj kev yog qhov tseem ceeb ntawm cov cuab yeej siv, thiab npaj tau LiPF6 muaj siab zoo thiab zoo zoo, thiab tsim nyog rau high-end lithium roj teeb ntau lawm. Txawm li cas los xij, txoj kev npaj ua tiav tau muaj kev xav tau rau cov khoom siv thiab kev lag luam, thiab HF ntxiv rau hauv LiPF6 muaj kev cuam tshuam rau kev ua haujlwm ntawm lub roj teeb.
Lwm txoj kev loj hlob ntau rau LiPF6 yog txoj kev sib pauv ntawm chestnut. Xa mus rau ib hom kev sib raug zoo ntawm tus hexafluorophosphate nrog lub lithium-compound compound hauv ib qho tshuaj organic kom tau LiPF6. Lub ntsiab ntawm txoj kev ion exchange yog tias nws yog qhov yooj yim thiab yooj yim, tiam sis qhov teeb meem purity LiPF6 nws daim ntawv thov dav.
1.2.2 Lithium ntsev
Tam sim no, muaj cov tshuab lithium ntsev electrolyte uas muaj kev nyab xeeb thiab kev ua haujlwm zoo rau qhov ua tau zoo. Piv nrog rau cov tshuaj electrolyte lithium ntsev LiPF6, txawm tias lub peev xwm peev xwm tsis muaj peev xwm sib tw nrog LiPF6, lawv muaj kev pom zoo hauv ntau yam, xws li, LiBOB? muaj zoo electrochemical stability thiab thermal stability, muaj peev xwm hnov mob nrog tej kuab tshuaj los tsim kom muaj kev ruaj khov? SEI? membrane, uas tuaj yeem ua pob ntseg tom qab rov ua kev ntawm lub zog. LiFSI yog lub lithium roj teeb uas muaj roj ntsha nrog kev ua haujlwm zoo. Nws muaj cov khoom zoo heev thiab zoo sib xws nrog cov ntaub ntawv electrode. LiBF4 muaj tshuaj lom neeg thiab thermal stability dua li LiPF6, thiab nws txoj kev nyab xeeb yog qhov zoo tshaj plaws. Txawm li cas los xij, ntau cov ntaub ntawv pov thawj pom tias muaj qee qhov kev txiav txim siab tsis tau siv cov lithium ntsev. Piv txwv li, LiFSI yog ib qho yooj yim ua rau txhuas txhuam hniav. LiBF4 muaj ib lub voj voog luv me me, muaj kev sib raug zoo nrog lithium ions, thiab tsis muaj zog. Nws tsis zoo hauv kev ua tau raws li lub lithium ion roj teeb siv los ua ib qho kua roj electrolyte lithium ntswg nkaus xwb. Yog li, lithium ntsev ntawm cov qauv sib txawv thiab ntau cov qauv muaj compounded, yog li ntawd lub composite electrolyte exhibits cov khoom zoo heev uas tsis muaj los ntawm cov khoom siv yooj yim, yog li kev txhim kho electrolyte kev kawm ntawm ntau yam.
1.2.3 Cov txiaj ntsig thiab qhov tsis zoo ntawm cov lithium ntsev ntau
LiBF4: kev kub ntxhov siab tsis zoo, tab sis pheej yig thiab tsawg zog;
LiPF6: Cov kev ua tau zoo dua qub yog qhov zoo dua, thiab qhov tsis zoo yog kev nqus dej thiab kev ywj pheej;
LiBOB: kev kub kub yog qhov zoo dua, tshwj xeeb tshaj yog inhibiting qhov kev puas tsuaj ntawm qhov hnyav rau qhov tsis zoo electrode, tab sis lub solubility yog tsawg;
LiFSI: tsis yog tsuas yog kev phooj ywg, tab sis kuj muaj kev thermal stability zoo, rhiab heev rau noo noo, thiab hluav taws xob conductivity;
LiPF2: Txhim kho siab kub thev kev ua tau zoo thiab kev ua tau zoo, kev tawm cov khoom kub tsis tshua kub, thiab kev tiv thaiv kev tiv thaiv thiab kev muaj peev xwm ntawm kev lithium roj teeb;
LiTFSI: zoo electrochemical stability, siab ionic conductivity, zoo thermal stability, thiab nyuaj rau hydrolyze;
LiTDI: Muaj tus lithium ion migration naj npawb, txo tus nqi ntawm lithium ntsev thiab txo nqi roj teeb.
1.3.1 Additives
Muaj ntau ntau hom tshuaj ntxiv, thiab cov lithium ion roj teeb ntau lub tuam txhab muaj cov kev cai sib txawv ntawm txoj kev siv thiab kev ua haujlwm ntawm lub roj teeb, thiab qhov tseem ceeb ntawm cov khoom siv ntxiv yog qhov txawv. Feem ntau, cov khoom siv feem ntau yog cov teebmeem nram qab no:
(1) Zaj dab neeg ua yeeb yam ntxiv
Cov cwj pwm uas tsis muaj zog hauv kev ua duab xws li SO2, CO2, thiab CO yuav pab txhawb tsim kom muaj ib daim ntawv tso cai, thiab ntxiv rau ib qho tshuaj xws li LiI lossis LiBr kuj tseem tuaj yeem txhim kho cov duab kos.
Organic-forming additives: cov tshuaj fluorinated, chlorinated thiab brominated organic xws li anisole los yog nws cov halivated derivatives yuav pab txhim kho lub voj voog ntawm lub roj teeb thiab txo qhov peev xwm ua tsis tau ntawm lub roj teeb. Ntawm lawv, vinylene carbonate (VC) yog ib qho yeeb yaj kiab zoo-ua tus quav ntxiv.
(2) txo cov dej thiab HF cov kua qaub nyob hauv cov electrolyte
Lub carbodiimide compound muaj peev xwm tiv thaiv tau lub hwjchim ntawm LiPF6 mus rau cov kua qaub. Tsis tas li ntawd, qee cov hlau oxides xws li Al2O1, MgO, BaO, Li2CO1, CaCO1 thiab cov zoo li yuav raug tshem tawm HF.
(3) Tiv thaiv kom tsis txhob muaj nqi thiab overdischarge additives
Cov khoom sib xws xws li cov organic amines thiab imines, biphenyls, thiab carbazoles yog siv los ntxiv cov khoom los tiv thaiv overcharge thiab overdischarge.
(4) Taub nplhaib lo xim ntxiv
Organophosphorus compounds xws li tetrapropoxysilane (TPOS), tetramethoxysilane (TMOS), organofluorine compounds, thiab halogenated alphos phosphates yog siv nplaim hluav taws kub nyob hauv high boiling point high flash point non-flammable compounds.
(5) Txhim kho cov ntsuas kev kub ntxhov
N, N-dimethyltrifluoroacetamide, organic boride, fluorine-muaj carbonate thiab lwm yam uas tsis muaj viscosity, high point taw tes yog lig rau kev txhim kho kub tsis ua hauj lwm ntawm lub roj teeb.
(6) Cov khoom siv ntau yam
Tom qab 12-crown-4 tau ntxiv rau PC hnyav, SEI zaj duab xis ntawm lub electrode interface tau muab kho kom txo tau thawj thawj zaug tsis muaj peev xwm ntawm lub electrode. Ntxiv ntawm cov tshuaj fluorinated organic solvents thiab halogenated phosphates xws li BTE thiab TTFP rau cov electrolyte tsis tsuas contributes rau tus tsim ntawm SEI zaj duab xis, tab sis kuj muaj ib qho lossis tseem ceeb nplaim retardancy rau cov electrolyte.